Hydraulic pump for vehicles controllable by handlebars

ABSTRACT

A master cylinder which has an unusual ability to limit space requirements, to be fitted in vehicles controllable by handlebars, comprises a cylinder body provided with a seat for housing a portion of the handlebar. A chamber for slidably housing a piston extends along an axis inside the cylinder body. A manual control lever which acts on the piston is mounted on the cylinder body for pivoting about its fulcrum in a plane. The axis along which the chamber for slidably housing the piston extends intersects the plane of pivoting of the control lever at a point.

FIELD OF THE INVENTION

The subject of the present invention is a master cylinder for vehiclescontrollable by means of handlebars, comprising a cylinder body having aseat for housing a portion of the handlebar, a chamber for slidablyhousing a piston, the chamber extending along an axis inside thecylinder body, and a manual control lever which acts on the piston andis intended to pivot about its fulcrum in a plane.

BACKGROUND OF THE INVENTION

More particularly, the invention relates to a master cylinder formotor-vehicle brakes or clutches. In fact, as is known, in motorvehicles such as, for example, motorcycles, the brake generallyassociated with the front wheel is operated by means of a mastercylinder mounted on the handlebars in the vicinity of one of the handgrips, conventionally the right-hand hand grip of the motorcycle.

Similarly, the clutch can also be operated by means of a master cylindermounted on the handlebars on the opposite side to the brake mastercylinder, that is, on the left-hand side of the motorcycle.

A master cylinder of the type described above is generally constitutedby a cylinder body in which a chamber is formed for housing a piston.When the piston is operated by the driver, it acts on a working fluidcontained in the respective brake or clutch system.

The chamber is arranged in communication with a reservoir which holdsthe working fluid and may be formed integrally with the cylinder body ormay be separate and connected thereto by an external pipe.

A master cylinder of the above-mentioned type also has a control leverwhich is mounted for pivoting on the cylinder body and is intended toact on the piston. This control lever faces the respective hand grip ofthe handlebar on which the master cylinder is mounted and is operated bythe driver by being pivoted about its fulcrum. In known mastercylinders, as the control lever pivots about its fulcrum, it defines aplane which generally includes the axis along which an end portion ofthe handlebar extends, in the region of the hand grip to be gripped bythe driver. The axis along which the chamber housing the piston extendsand which is also defined as the axis of the master cylinder, also liesin the said plane, or in a plane parallel thereto.

In order to make the gripping of the control lever ergonomic for thedriver, this plane, which contains both the axis of the end portion ofthe handlebar and the axis of the cylinder, is inclined to a horizontalplane, for example, defined by the plane in which the free surface ofthe working fluid is disposed inside the reservoir. The extent of thisinclination is about 15° downwards in the direction of travel of thevehicle, this statement meaning that a point in the plane in thevicinity of the control lever is disposed below a point in the plane inthe vicinity of the end portion of the handlebar, as described morespecifically below.

In the field of motor vehicles, and motorcycles in particular, there isa particular need to have an especially compact and aestheticallypleasing external design which at the same time satisfies functionalneeds, for example, connected with aerodynamic requirements.

From this point of view, the above-mentioned master cylinders have manydisadvantages. For example, both technical and aesthetic disadvantagesconnected mainly with problems of space requirements are encountered inmounting these cylinders on a motor vehicle. Motor vehicles in fact havebodywork elements such as hoods, windscreens, hand guards, fairings orother components which extend up to the vicinity of the ends of thehandlebars where the hand grips, the master cylinders, and generallytheir respective reservoirs, are positioned. In particular, in the caseof cylinders in which the cylinder body and the reservoir are formedintegrally, the reservoir is generally positioned above the chamberhousing the piston and may even reach considerable dimensions when themaster cylinder is of a size suitable for operating, for example, twobrake calipers.

Since the bodywork elements have to be designed to envelop thehandlebars completely, housing both the master cylinders and thereservoirs, ugly protuberances are inserted in the vicinity of thelatter and, as well as affecting the appearance of the bodywork, thesealso affect its functional and aerodynamic aspects.

The problem upon which the present invention is based is that ofproposing a master cylinder for vehicles controlled by means ofhandlebars which has structural and functional characteristics such asto satisfy the above-mentioned requirements and, at the same time, toovercome the disadvantages mentioned with reference to the prior art.

SUMMARY OF THE INVENTION

This problem is solved by a master cylinder for vehicles controllable bymeans of handlebars according to Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and the advantages of the master cylinderaccording to the invention will become clear from the followingdescription of a preferred embodiment thereof, provided by way ofnon-limiting example with reference to the appended drawings, in which:

FIG. 1 shows, from above, a handlebar portion on which a master cylinderaccording to the present invention is fitted,

FIG. 2 is a partially-sectioned view of the cylinder of FIG. 1, taken inthe plane of the line II—II, and

FIG. 3 shows a possible variant of the cylinder of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, a master cylinder, generally indicated1, comprises a cylinder body 2.

In the embodiment illustrated in FIGS. 1 and 2, the cylinder body 2 isformed as a unitary element extended by a yoke 3, a handlebar seat 4,and a reservoir 5.

A possible datum relating to the master cylinder 1 is obtained by avertical axis V and a horizontal plane P, defined as stated below.

The reservoir 5 in fact contains a working fluid, this definitionmeaning a fluid of any type suitable for use in braking systems orclutch systems, for example, for applications in vehicles controllableby means of handlebars. This fluid is disposed in the reservoir 5,defining a free surface which, since it is subject to the effect ofgravity, is disposed in a horizontal plane P, the line of which isindicated in FIG. 2.

To prevent leakage of fluid from the reservoir and to utilize itsmaximum capacity, the reservoir is mounted on a motor-vehicle handlebarso as to have its walls substantially perpendicular to the horizontalplane P defined by the free surface of the fluid. When the fluid is heldin the reservoir in working conditions, a vertical axis V, perpendicularto the plane P, is thus defined.

A first, upwardly-directed vector V′ is defined along this vertical axisV, this definition meaning a vector directed away from the free surfaceof the fluid, generally towards the opening of the reservoir. Similarly,a second, downward vector V″ is defined along the vertical axis V, thisdefinition meaning a vector directed from the free surface of the fluid,into the fluid, generally towards the bottom of the reservoir.

Relative to a horizontal reference plane, for example, the plane Pcorresponding to the free surface of the working fluid in the reservoir,the first vector V′ consequently defines an upper half-space and thesecond vector V″ defines a lower half-space.

A control lever 6 is mounted for pivoting in the yoke 3 so as to face anend portion of a handlebar 7 of the motor vehicle and, in particular, ahand grip 8 to be gripped by the driver. The shape and mounting of thecontrol lever 6, which are dictated by ergonomic considerations, aresubstantially conventional and the lever ratio remains unchanged fromthat of known master cylinders. In particular, the control lever 6comprises a head 6 a mounted for pivoting in the yoke 3. A slenderportion 6 b extending from the head is intended to be gripped by thedriver whilst he is gripping the corresponding hand grip 8. The slenderportion 6 b has a curved shape designed to favour ergonomic gripping.The control lever 6 can pivot about its fulcrum towards thecorresponding hand grip 8 as a result of the force exerted by thedriver. When the driver releases the control lever 6 it can pivot awayfrom the respective hand grip 8 and return to the initial rest position.As the control lever 6 pivots about its fulcrum it defines a plane X theline of which is shown in FIG. 2. This plane is, for example, defined bythe rotation of an axis A—A extending through the fulcrum of the controllever 6 and interpolating the shape of the slender portion 6 b.

In greater detail, with reference to the end portion of the handlebar 7which is gripped by the driver, this portion extends along an axis 7 awhich, for reasons of ergonomics, preferably lies in the plane X ofpivoting of the control lever 6. In the embodiment shown in thedrawings, the axis 7 a of the end portion of the handlebar 7 coincideswith the axis of the continuation of the handlebar on which the mastercylinder 1 is mounted and, in the mounted condition, thus coincides withthe axis of the seat 4 of the master cylinder 1.

Moreover, to facilitate gripping of the control lever 6 by the driverand to enable the driver to adopt the correct position on the motorvehicle, the plane X is inclined downwards in the direction of travel ofthe vehicle, at about 15° to a horizontal plane. That is, with referenceto the horizontal plane parallel to the plane P and extending throughthe fulcrum of the control lever 6, the axis 7 a is disposed in theupper half-space relative to that plane, in the upward directionindicated by the first vector V′ of the axis V, as defined above.

The seat 4 is shaped so as to surround a portion of the handlebar 7. Inthe embodiment in question, the seat 4 is cylindrical in order tosurround the tubular structure of the handlebar 7 and extends along anaxis which, in the mounted condition, coincides with the axis of thehandlebar. As already stated above, in the embodiment illustrated in thedrawings, the axis of the seat 4 coincides with the axis 7 a of theportion of the handlebar 7 which is gripped, that is, which correspondsto the hand grip 8. The walls which define the seat 4 comprise threadedholes 9 for receiving screws 10 which clamp the structure of the mastercylinder 1 to the handlebar and keep the plane X inclined at theabove-mentioned angle.

In FIGS. 1 and 2, the reservoir 5 is formed integrally with the cylinderbody 2 and contains the working fluid, as does the system as a whole,not shown. The reservoir is closed at the top by a cover 11 with anassociated flexible diaphragm, not shown, to which the working fluidcontained in the reservoir adheres. The fluid thus never comes intodirect contact with the outside atmosphere. One of the walls of thereservoir 5 advantageously comprises a window 5 a which enables thelevel of fluid in the reservoir to be checked from the exterior.

Inside the cylinder body 2 there is a chamber 12, connected to thereservoir 5 by means of ducts 13 through which the working fluid canpass from the reservoir 5 to the chamber 12. The chamber 12 also has aconventional delivery opening and a bleeding vent, the latter beingindicated 14 in FIG. 2.

The chamber 12 has a cylindrical shape extending along an axis 15, alsogenerally indicated as the axis of the cylinder. In the embodiment shownin FIG. 2 in particular, the axis 15 is disposed below the seat 4 forhousing the handlebar 7, in the downward direction defined by the secondvector V″ of the vertical axis V. This means that, in the mountedcondition, the axis 15 is disposed below the portion of the handlebar 7to which the cylinder body 2 is clamped.

In the embodiment illustrated, the axis 15 is also arrangedperpendicular to the axis of the portion of the handlebar 7 on which thecylinder body 2 is clamped and advantageously lies in a horizontal planedisposed entirely below the handlebar. The axis 15 and the plane Xdefined by the pivoting of the control lever 6 are advantageouslyarranged so as to intersect at a point B. The term “intersect” meaningthat the axis 15 and the plane X have in common a single point, that isthe point B, and that the axis 15 does not therefore lie in the plane Xor in a plane parallel thereto.

In the embodiment shown in FIG. 2, the projection of the axis 15 ontothe line of the plane X preferably meets the control lever 6 at anintermediate point between the fulcrum and the free end of the lever, sothat the lever is a second-order lever.

The chamber 12 is advantageously positioned entirely below the seat 4,and hence below the handlebar 7, in the direction of the second vectorV″ of the axis V. The upper end of the reservoir 5 is correspondinglyarranged slightly above the seat 4 and the space occupied by thereservoir occupies substantially the vertical dimension of the seat, andhence of the handlebar 7. In particular, the reservoir 5 is positionedin front of the seat 4, that is, in a position between the seat 4 andthe control lever 6. Moreover, with respect to the position of themaster cylinder 1 on the handlebar 7, and hence on the vehicle, thereservoir 5 is positioned in front of the seat 4, and hence in front ofthe handlebar 7, “in front” defining a position which, relative to theseat 4 and to the handlebar 7, is disposed in the direction of forwardtravel of the vehicle.

In accordance with the foregoing description, the cylinder body 2,together with the seat 4 and the reservoir 5, define a compactstructure. In particular, in a cross-section such as that shown in FIG.2, which is taken in a plane perpendicular to the plane X and containingthe axis 15, the relative positions of the above-mentioned threeelements are such that the projection of the seat 4 along a verticalaxis V falls at least partially on the chamber 12 and the projection ofthe seat 4 along a horizontal axis P falls at least partially on thereservoir 5.

The chamber 12 houses a floating piston 16 which can move along the axis15, forming a seal against the walls of the chamber. More particularly,the piston 16 can move between a travel-limit, rest position shown inFIG. 2 and an advanced, operative position, not shown. In thetravel-limit, rest position, the piston 16 is urged by a return spring17 into a position corresponding to the maximum distance. from thehandlebar whereas, in the advanced, operative position, the piston 16overcomes the return spring 17 and the pressure of the fluid containedin the chamber 12 and in the system, and advances towards the handlebar.

This movement is brought about, by means of a rod 18, by the pivoting ofthe control lever 6. The rod 18 has a first portion 18 a substantiallyinside the chamber 12 and interacting with the piston 16 and a secondportion 18 b which extends out of the chamber 12 and, in particular,towards the control lever 6. The two portions are defined substantiallyby a dust-protection cap 19 which seals the chamber 12 from the outsideatmosphere.

The interaction between the first portion 18 a and the piston 16 takesplace by means of a connection 20 formed by the coupling between a seatformed at the end of the piston and a rounded end of the first portion18 a of the rod.

The second portion 18 b terminates in a ball joint 21 for connectionbetween the rod 18 and the control lever 6. In particular, the balljoint 21 is formed by a substantially spherical end of the secondportion 18 b which is coupled with a seat of matching shape formed inthe body of the control lever 6. The ball joint 21 and, in particular,its centre C, meaning the centre of the substantially spherical end ofthe second portion 18 b, is advantageously disposed below the point Bwhen the piston 16 is in the travel-limit, rest position (FIG. 2).Moreover, the centre C of the ball joint 21 is advantageously disposedabove the point B when the piston 16 is in the advanced, operativeposition. With regard to the datums indicated above, a position belowthe point B is a position which, relative to a horizontal planeextending through the point B, is disposed in the lower half-spacedefined by the direction of the second vector V″ of the axis V.Similarly, a position above the point B is a position which, withrespect to a horizontal plane extending through the point B, is disposedin the upper half-space defined by the direction of the first vector V′of the axis V.

The way in which the master cylinder according to the present inventionis used is described below with particular reference to a mastercylinder for operating the braking system, although the followingdescription is equally applicable to the clutch-operating cylinder.

When it is necessary to brake, the driver of the vehicle, whilst stillgripping the hand grip 8, grips the control lever 6 and pivots it aboutits fulcrum, moving it towards the handlebar. The control lever 6 pivotsin the plane X, interacting with the rod 18 and consequently with thepiston 16.

In particular, the control lever 6 pushes the rod 18 in the region ofthe ball joint 21, causing it to slide in the plane X and hence along apath having both a horizontal component and a vertical component. Themovement of the rod 18 pushes the piston 16 from the travel-limit, restposition to the advanced, operative position, overcoming the returnspring 17 and the pressure of the working fluid, which graduallyincreases.

As a result of the pivoting of the control lever 6 which brings aboutthe movement of the piston 16 between the travel-limit, rest positionand the advanced, operative position, the ball joint 21 and, inparticular, its centre C, moves substantially along the plane X betweena first position slightly below the intersection point B and a secondposition slightly above the intersection point B. In an intermediateposition of the pivoting of the control lever 6, the ball joint 21 is ina position in which the centre C preferably coincides with the point Band the rod 18 is correspondingly aligned with the axis 15 of thechamber 12. This coinciding arrangement occurs because the point B ofthe intersection of the axis 15 and the plane X lies on the path of thecentre C of the ball joint 21, at an intermediate point thereof.

When the driver releases the control lever 6, the ball joint 21 returnsto the position shown in FIG. 2 and the piston 16 is correspondinglyurged back to the travel-limit, rest position by the return spring 17.

As can be appreciated from the foregoing description, the mastercylinder according to the present invention satisfies theabove-mentioned need to limit the space requirements owing to thepresence of the cylinder body and of the reservoir and to solve theproblems described with reference to the prior art.

In particular, the fact that the plane X of pivoting of the controllever 6 and the axis 15 of the chamber housing the piston intersectenables the chamber 12 to be positioned entirely below the handlebar,thus lowering the reservoir to the level of the handlebar, in front ofthe handlebar. The novel configuration adopted in fact enables thechamber housing the piston to be lowered, in comparison withconventional master cylinders, by an amount at least equal to theoutside diameter of the portion of the cylinder body which surrounds thechamber, at the same time making the cylinder body more compact.

Excessive space requirements are thus avoided, particularly above thehandlebar, enabling the cylinder to be incorporated in a motor vehiclemore easily and improving both the aerodynamics and the aesthetics ofthe motor vehicle.

A further advantage of the master cylinder according to the presentinvention lies in the simplicity of its structure, enabling the problemsmentioned with reference to the prior art to be solved without, however,altering the shape and functionality either of the vehicle as a whole,or of the respective brake/clutch systems in particular.

In addition to the foregoing advantages, the positioning of the rod 18reduces wear of the piston. The fact that the centre C of the ball joint21 moves from a position slightly below the point B to a positionslightly above the point B in fact enables the two points preferably tocoincide when the control lever, and correspondingly the rod 18 and thepiston 16, are in an intermediate position of their travel. Thecoincidence of the two points in fact leads to an alignment between therod 18 and the piston 16 in the intermediate position, which correspondsto the position which is reached most frequently during the life-cycleof a master cylinder and at which the forces in play are considerable.

The disalignment between the rod and the piston is in fact toleratedbetter in the initial stage of the pivoting of the control lever 6since, at this stage it corresponds substantially to the taking-up ofplay during which the forces in play are limited. The disalignmentbetween the rod and the piston is also better tolerated in the finalstage of the pivoting of the control lever 6. In fact, although thisstage corresponds to the stage at which the forces in play are greatest,it is reached with difficulty during normal use.

Naturally variants and/or additions may be provided for the embodimentdescribed and illustrated above.

As an alternative to the arrangement shown in FIGS. 1 and 2, the plane Xin which the control lever 6 pivots may not include the axis 7 a of thehandlebar 7 but nevertheless still intersects the axis 15 of the chamberfor housing the piston 16.

The reservoir 5 may be formed separately from the portion of thecylinder body which houses the chamber 12 and which is neverthelessdisposed in a lower position than in conventional cylinders by virtue ofthe smaller size and greater compactness offered by the cylinderaccording to the present invention. This possible solution is shown inFIG. 3 in which the separate reservoir, not shown, is connected to thechamber 12 by means of the ducts 13 and external pipes shown partiallyand indicated 13 a.

As an alternative to the embodiments shown in the drawings, the axis 15of the chamber 12 may be arranged in a plane which is not horizontal butnevertheless intersects the plane X. In this case, the angle α ofintersection between the axis 15 and the plane X is preferably between10° and 20°, “angle of intersection” defining the angle between the axis15 and the line of the plane X lying in the plane perpendicular to theplane X and containing the axis 15.

Moreover, the path of the centre C of the ball joint 21 may not meet thepoint B. The point C consequently moves between a position slightlybelow the point B to a position slightly above the point B passingthrough an intermediate position which is at the same level as the pointB but does not coincide therewith.

In a possible embodiment, not shown, the axis of the seat 4 may be otherthan the axis 7 a of the end portion of the handlebar 7, that is, of theregion of the hand grip 8.

As stated above, in the embodiment shown in the drawings, the axis 15 ofthe chamber 12 is disposed below the seat 4 so that the chamber is alsoentirely below the seat and the handlebar. According to an embodimentwhich is not shown, the axis 15 may still be below the seat 4 whilst thechamber 12 may be only partially below the seat 4.

In order to satisfy contingent and specific requirements, an expert inthe art may apply to the above-described preferred embodiment of themaster cylinder many modifications, adaptations and replacements ofelements with other functionally equivalent elements without, however,departing from the scope of the following claims.

1. A master cylinder for vehicles controllable by handlebars,comprising: a cylinder body provided with a seat for housing a portionof the handlebar, a chamber for slidably housing a piston, the chamberextending along an axis inside the cylinder body, and a manual controllever which acts on the piston and is adapted to pivot about a fulcrumand within a plane, wherein the axis intersects the plane of pivoting ofthe control lever at a single point and wherein said axis along whichsaid chamber for slidably housing the piston extends and said plane ofpivoting of said control lever are inclined by an angle of between 10°and 20°.
 2. A master cylinder according to claim 1 in which said axis isdisposed in a horizontal plane.
 3. A master cylinder according to claim1 in which said axis is disposed below the seat for housing thehandlebar.
 4. A master cylinder according to claim 3 in which thechamber for slidably housing the piston is disposed at least partiallybelow the seat for housing the handlebar.
 5. A master cylinder accordingto claim 3 in which the chamber for slidably housing the piston isdisposed entirely below the seat for housing the handlebar.
 6. A mastercylinder according to claim 1 in which the seat for housing a portion ofthe handlebar extends along an axis which lies in the plane of pivotingof the control lever.
 7. A master cylinder according to claim 1 in whicha reservoir containing a working fluid is provided and is disposed infront of the seat for the handlebar.
 8. A master cylinder according toclaim 7 in which the reservoir is formed integrally with the cylinderbody.
 9. A master cylinder according to claim 8 in which, in a sectiontaken in a second plane perpendicular to the plane of pivoting andcontaining the axis, the chamber, the seat, and the reservoir haverelative positions such that a projection of the seat along a verticalaxis falls at least partially on the chamber and a projection of theseat along a horizontal axis falls at least partially on the reservoir.10. A master cylinder according to claim 1 in which the control leveracts on the piston by means of a rod connected to the control lever bymeans of a ball joint defining a centre.
 11. A master cylinder accordingto claim 10 in which the point of intersection between the axis and theplane lies on the path of the centre of the ball joint.
 12. A mastercylinder according to claim 11 in which the point of intersectionbetween the axis and the plane lies at an intermediate point on the pathof the centre of the ball joint.
 13. A master cylinder according toclaim 1 in which said axis is disposed in a horizontal plane.
 14. Amaster cylinder according to claim 1 in which said axis is disposedbelow the seat for housing the handlebar.
 15. A master cylinderaccording to claim 2 in which said axis is disposed below the seat forhousing the handlebar.
 16. A master cylinder according to claim 1 inwhich the seat for housing a portion of the handlebar extends along anaxis which lies in the plane of pivoting of the control lever.
 17. Amaster cylinder according to claim 2 in which the seat for housing aportion of the handlebar extends along an axis which lies in the planeof pivoting of the control lever.
 18. A master cylinder according toclaim 3 in which the seat for housing a portion of the handlebar extendsalong an axis which lies in the plane of pivoting of the control lever.19. A master cylinder according to claim 1 in which the control leveracts on the piston by means of a rod connected to the control lever bymeans of a ball joint defining a centre.
 20. A master cylinder accordingto claim 19 in which the point of intersection between the axis and theplane lies on the path of the centre of the ball joint.
 21. A mastercylinder according to claim 20 in which the point of intersectionbetween the axis and the plane lies at an intermediate point on the pathof the centre of the ball joint.
 22. A master cylinder according toclaim 2 in which the control lever acts on the piston by means of a rodconnected to the control lever by means of a ball joint defining acentre.
 23. A master cylinder according to claim 22 in which the pointof intersection between the axis and the plane lies on the path of thecentre of the ball joint.
 24. A master cylinder according to claim 23 inwhich the point of intersection between the axis and the plane lies atan intermediate point on the path of the centre of the ball joint.